JPH053163A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor device, where a BPSG film adequate in concentration to induce an enough glass flow is thermally treated for flattening without separating particles and then an aluminum wiring is formed high in yield. CONSTITUTION:A process wafer 6 is a semiconductor substrate where a a BPSG film is formed so as to improve an interlayer insulating film in evenness. Silicon substrates (dummy wafers 7) are placed near on both ends of a quartz port 8 so as to make a gas flow uniform. Process wafers 6 are mounted between the dummy wafers located on the ends of the port 8. When the process wafers 6 are arranged so as to be separate from each other by a space of 9/16 inch, boron, phosphorus, or the like suspended in a heat treating atmosphere can be lessened in concentration relatively to the process wafers 6, and the BPSG film can be lessened in number of separated particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of heat treating an oxide film containing boron and phosphorus as impurities.

[0002]

2. Description of the Related Art In recent years, as the miniaturization of semiconductor devices has progressed, the steps of wirings and the like after etching have become larger. Especially dynamic random access memory (DRA
The stack method has been adopted as the storage node forming method of (M), and the multilayer wiring has been used as the wiring method.To easily form the photolithographic pattern of the upper layer and to easily etch the upper layer film, a high It is necessary to flatten the steps. Therefore, boron phosphorus silicate glass (Borophore) is an oxide film containing boron and phosphorus as impurities.
sposilicate Glass: Hereinafter referred to as BPSG. ) And deposit 90
A method for flattening by reflowing BPSG by performing heat treatment at a temperature of 0 ° C or higher has been developed. This technology is reported, for example, in Oki Electric R & D No. 130, Vol. 53, page 79 (April 1986), and Oki Electric R & D, No. 140, Vol. 55, page 123.

As a conventional heat treatment method for BPSG, the following method is used. FIG. 16 is a process diagram of this conventional oxide film heat treatment method, and shows the position of the substrate 83 placed on the boat 82 with respect to the core tube 81 in each step of thermal history. In FIG. 16, 81 is a core tube, 82 is a boat, and 83 is a substrate on which the BPSG is deposited (hereinafter referred to as substrate) mounted on the boat 82. FIG. 17 is a heat history diagram of the conventional heat treatment method for an oxide film.

The operation of the conventional heat treatment method for an oxide film having the above structure will be described below. Insertion process
At 91, the substrate 83 is placed on the boat 82 and inserted into the core tube 81 as shown in FIGS. 16 (A) to 16 (B). Next, after the heating process 92 is completed, in the heat treatment process 93, heat treatment is performed at a temperature of 900 ° C. or higher. During the heat treatment process 93, the BPSG on the substrate 83 becomes flat due to surface tension and the like over time because its viscosity coefficient becomes small. Then the retrieval process 94
In FIG. 16B to FIG. 16C, the substrate 83 is taken out into the atmosphere together with the boat 82.

[0005]

However, in the above-mentioned configuration, particularly when the substrate is taken out, the temperature decreasing rate is slow, and the substrate is exposed to the atmosphere. Precipitates containing phosphorus and oxygen as the main components and having a diameter of about 0.1 um to 10 um are generated on the surface of BPSG due to the reaction with boron and phosphorus therein or the crystal growth in BPSG. This precipitate is reflected by high-speed electron diffraction (Reflecti
On High Energy Electron Diffraction (RHEED) and electron probe X-ray microanalyzer (EPMA) analysis results show that the precipitates are crystals containing a large amount of phosphorus and oxygen. These results are reported by the present inventors in the autumn 1990, 51st Annual Meeting of the Society of Applied Physics, Lecture No. 26a D 5 / ii.

FIG. 18 shows the principle of generation of this precipitate.
FIG. 18A shows a principle diagram regarding vapor phase growth, and FIG. 18B shows a principle diagram regarding solid phase growth. In FIG. 18, 101 is BPS
G and 102 indicate precipitates. The principle of occurrence of precipitation will be described below with reference to FIG. In FIG. 18 (A), oxygen and water vapor in the atmosphere react with boron and phosphorus vaporized from BPSG in the gas phase to grow a precipitate. In FIG. 18B, the phosphorus oxide or boron oxide in BPSG101 reacts in BPSG in a solid phase within a certain temperature range of BPSG, and a precipitate grows.

As is clear from the above, the above-mentioned structure has a problem in that the flatness in the post-process is deteriorated due to the generation of precipitates, and the manufacturing yield is extremely deteriorated due to pattern defects, etching defects and the like. Had.

The present invention solves the above-mentioned problems of the prior art, and heat treatment for flattening a BPSG film having a concentration that causes a sufficient glass flow without causing precipitation of particles. It is an object of the present invention to provide a method for manufacturing a semiconductor device in which wiring is formed with good yield after that.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein a plurality of semiconductor substrates are loaded into a heat treatment furnace in a state in which a plurality of semiconductor substrates are set in a semiconductor substrate carrying jig at predetermined intervals. Then, a heat treatment is performed in a heat treatment furnace in accordance with a predetermined temperature profile to reflow the dielectric containing impurities formed on each semiconductor substrate to flatten the substrate surface. In the manufacturing method, the predetermined interval is set to an interval at which impurities evaporated during heat treatment cannot adhere to adjacent substrates.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein a plurality of semiconductor substrates are set in a semiconductor substrate carrying jig at predetermined intervals and are loaded into a heat treatment furnace, and then the heat treatment furnace is set in the heat treatment furnace. In the method of manufacturing a semiconductor device, the method includes the step of performing a heat treatment according to a predetermined temperature profile to reflow a dielectric containing impurities formed on each semiconductor substrate to flatten the substrate surface. One of the control factors in the process is set to a condition that impurities evaporated from the dielectric during heat treatment cannot be crystallized to suppress the generation of precipitates on the semiconductor substrate.

It is characterized in that the one control factor is any one of an atmosphere during the heat treatment, a flow rate of an atmosphere gas during the heat treatment, a furnace pressure during the heat treatment, and a temperature lowering rate in a temperature lowering process of the heat treatment.

[0012]

According to the method of manufacturing a semiconductor device according to the first aspect of the present invention, by increasing the distance between the semiconductor substrates, the concentration of boron, phosphorus, etc. floating in the heat treatment atmosphere can be reduced. Can be made relatively thin, and heat treatment for planarization is performed without causing precipitation of particles, and then wiring such as aluminum is formed with good yield, and the characteristics of the element formed are It can be significantly improved.

According to the method of manufacturing a semiconductor device according to the second aspect of the present invention, a plurality of semiconductor substrates are loaded into the heat treatment furnace in a state where they are set in the semiconductor substrate carrying jig at predetermined intervals, and the heat treatment furnace is loaded. One control factor in the step of performing a heat treatment in accordance with a predetermined temperature profile to reflow the dielectric containing impurities formed on each semiconductor substrate to flatten the substrate surface,
The conditions under which the impurities evaporated from the dielectric during the heat treatment cannot be crystallized are set to suppress the generation of precipitates on the semiconductor substrate. If the atmosphere during heat treatment is selected as one control factor, it is possible to terminate the dangling bonds of the atoms that compose the dielectric film containing impurities such as the BPSG film, and planarize without causing the precipitation of particles. Heat treatment is performed, and then wiring such as aluminum is formed with a good yield, so that the characteristics of the element thus formed can be remarkably improved.

If the flow rate of the atmospheric gas during the heat treatment is selected as one control factor, boron and phosphorus vaporized from the reactive element BPSG are blown off from the BPSG surface, and the cooling effect is enhanced, so that precipitates are formed. Does not occur.

If the furnace pressure during the heat treatment is selected as one of the control factors, precipitates will not be generated by removing the reactive element from the BPSG surface.

Further, if the temperature lowering rate in the temperature lowering process of the heat treatment is selected as one control factor, precipitates are not generated by lowering the temperature range in which the precipitates are generated without giving the time for growing the precipitates.

[0017]

(Embodiment 1) FIG. 1 is a cross-sectional view showing a processed wafer placed on a boat of a heat treatment apparatus in a first embodiment of the present invention. FIG. 2 is a sectional view showing a processed wafer placed on a boat of a heat treatment apparatus in a conventional example.

FIGS. 1 (a) and 2 (a) show a dummy wafer 7 and a processed wafer 6 mounted on a semiconductor substrate carrying jig 8 for an electric furnace (hereinafter referred to as a boat 8). 1 (b), 2
(B) is an enlarged view of FIG. 1 (a) and FIG. 2 (a), respectively.

The processed wafer 6 is a semiconductor substrate on which a BPSG film is formed in order to improve the flatness of the interlayer insulating film. In both the present embodiment and the conventional case, a silicon substrate (dummy wafer 7) is placed near both ends of a quartz boat in order to make the gas flow uniform. Dummy wafer 7 on both ends
The processed wafer 6 is placed between them.

Since the deposited particles of the BPSG film grow due to the deposition of boron or phosphorus in the vapor phase, conventionally, as shown in FIG. Although the concentration of boron, phosphorus, etc. increased, the deposited particles of the BPSG film were generated, but if the spacing between the processed wafers 6 was set to 9/16 inch as shown in FIG. It is possible to reduce the concentration of floating boron, phosphorus, etc., and eliminate the deposited particles of the BPSG film.

FIG. 3 is a plot of the relationship between the wafer interval and the number of precipitated particles on a log scale in arbitrary units. The wafer intervals were 3/16 inch, 6/16 inch, and 9/16 inch. With the conventional wafer spacing of 3/16 inches, the number of precipitated particles is 10
Compared to 00, 6/16 inch is 3 digits less 0.8
The number is 0 for 9/16 inch. in this way,
It can be seen that the effect of reducing the number of precipitated particles is extremely large by setting the wafer interval to 6/16 inches or more.

(Embodiment 2) FIG. 4 shows profiles of the flow rate of gas flowing into the electric furnace and the electric furnace temperature in the heat treatment step in the second embodiment of the present invention.

In this example, from the point where the boat is inserted into the electric furnace (boat insertion step 9), the temperature stabilization period 1
0, heating process 11, and heat treatment period 14 (at 900 ° C, 30
Treatment in nitrogen 15SLM until the end of the treatment), and then in the temperature lowering process 12, nitrogen 13.5SLM, oxygen 1SLM, hydrogen 1SLM.
Is flowing. Five minutes from the start of flowing oxygen until the start of flowing hydrogen is a time (oxygen filling period 15) for filling the electric furnace with oxygen so that all the hydrogen reacts with oxygen. Similarly, 1 minute from when the flow of hydrogen is stopped to when the flow of oxygen is completed is the residual hydrogen reaction period 16 for not releasing unreacted hydrogen. By increasing / decreasing the temperature of the profile and flowing the gas, particles are not deposited even if the processing wafer interval is set to 3/16 inch as in the conventional case, and the yield is improved without deteriorating the throughput. Wiring such as aluminum can be made.

5 (a) to 5 (d) show the experimental results based on the second embodiment. From the heat treatment period to the cooling process,
Boat removal process, 1 field of view of microscope (magnification, 500
Indicates the number of precipitated particles that can be seen within the time. In both cases, the temperature rising period from the boat insertion to 900 ° C. is the same as in FIG. 4, and is not shown in FIGS. 5 (a) to 5 (d).

FIG. 5 (a) shows a heat treatment period in a pyrogenic atmosphere of 900.degree. C. in which the temperature is lowered from 900.degree. C. to 700.degree. C. in a nitrogen atmosphere, and FIG. 5 (b) shows a heat treatment period of 900.degree. 85
Pyrogenic atmosphere during cooling to 0 ° C, then nitrogen atmosphere from 850 ° C to 700 ° C, Fig. 5
(c) is a heat treatment period of 900 ℃, a pyrogenic atmosphere during the temperature decrease period to 800 ℃, then nitrogen atmosphere from 800 ℃ to 700 ℃, Figure 5 (d), heat treatment period of 900 ℃ Is a nitrogen atmosphere, and then a pyrogenic atmosphere is used during the temperature reduction period from 900 ° C to 700 ° C. The number of precipitated particles in one field of view of the microscope is 11, 0, 1 respectively.
The number is 0 and the number is 0, which is very small compared to the normal heat treatment method.

Further, comparing (a) with (b) and (c), rather than changing from a pyrogenic atmosphere to a nitrogen atmosphere at 900 ° C., a temperature of 900 ° C. to 850 ° C. or 800 ° C. in a pyrogenic atmosphere The treatment was more effective.
In (d), the heat treatment period is 900 ° C to 700 ° C in a nitrogen atmosphere.
Although only up to ℃ was carried out in a pyrogenic atmosphere, an equivalent effect was obtained by the same factor as in (b) or (c).

Such a pyrogenic atmosphere is BP
The reason for suppressing the particle deposition of the SG film will be described with reference to FIG. As shown in FIG. 6A, there are many unsaturated bonds 25, negatively charged boron 26, positively charged phosphorus 27, etc. in the BPSG film. It is considered that the precipitation of particles in the BPSG film is caused by the formation of new bonds such as these unsaturated bonds 25 during the heat treatment. When it is brought into contact with it in a pyrogenic atmosphere, H ₂ O molecules come into contact with the surface of the high-temperature BPSG film and decompose into hydrogen ions and hydroxide ions or hydrogen radicals and hydroxide radicals. As shown in (b), each of them penetrates into the BPSG film and 25
Alternatively, by terminating the negatively charged boron 26, the positively charged phosphorus 27, and the like, generation of new bonds is prevented, so that precipitation of particles is suppressed.

FIG. 7 is a cross-sectional view of a MOS transistor immediately after heat-treating a BPSG film according to this embodiment. In the conventional pyrogenic oxidation, as shown in FIG. 7, a polysilicon gate 19 under the BPSG film 17 and a contact hole 18 are formed.
There is a problem in that the source 21 and the drain 22 are oxidized through and the wiring resistance of the polysilicon gate increases. Here, an oxidized polysilicon gate, an oxidized source region, and an oxidized drain region are shown at 20, 23, and 24, respectively.

On the other hand, according to the second embodiment of the present invention, both the oxygen flow rate and the hydrogen flow rate are 1 SLM, the concentration of oxidizing species is extremely smaller than that of the conventional pyrogenic oxidation, and further, in the electric furnace. Since the temperature inside the electric furnace when it is a pyrogenic atmosphere is not the temperature during processing (here, 900 ° C) as in the past, but the temperature during cooling, the polysilicon gate below the BPSG film is In addition, the amount of oxidation of the source region, the drain region, etc. is reduced, and the wiring resistance of the polysilicon gate is not increased. Also, a pyrogenic atmosphere period 32
Is shorter, the oxygen flow rate is lower, and the hydrogen flow rate is lower.
The amount of oxidation of the 9, source 21, drain 22 regions, etc. is reduced. The concentrations of B ₂ O ₃ and P ₂ O _{5 in} the BPSG film used here are B ₂ O ₃ 11.8 mol% and P ₂ O ₅ 6.8 mol%, respectively. However, the concentration is not limited to this.

When a pyrogenic atmosphere was used throughout the temperature decreasing process from 900 ° C. to 700 ° C. (temperature decreasing rate 5 ° C./min, temperature decreasing time 40 minutes), the oxide film thickness on the silicon substrate was 10 nm. This oxide film thickness corresponds to 10 minutes with respect to the normal dry O ₂ oxidation at 900 ° C. As described above, there is no problem even if the pyrogenic atmosphere of this embodiment is used in the semiconductor process.

Although the processing temperature in this embodiment was 900 ° C., it may be 950 ° C. other than 900 ° C., 850 ° C. or 800 ° C. Further, the boat insertion temperature and the boat take-out temperature here are 800 ° C., but may be 750 ° C. or 700 ° C. Further, the boat insertion temperature and the boat extraction temperature do not have to be the same.

In this embodiment, the pyrogenic atmosphere period 32 is set in the temperature lowering process 12, but the unsaturated bond in the BPSG film may be terminated. Only a part of the heating process 11 may be performed. Also, heat treatment period 14
Alternatively, only a part of the heat treatment period 14 may be used. Alternatively, both the temperature raising process 11, the heat treatment period 14, the temperature lowering process 12, or all of them may be performed. Although nitrogen is used in this embodiment, a non-oxidizing atmosphere such as an inert gas such as argon or helium may be used. The flow rates of nitrogen, oxygen, hydrogen, etc. are not limited to this. Instead of water vapor, an oxidizing atmosphere such as a halogen compound such as hydrogen chloride (HCl) may be used.

(Embodiment 3) FIG. 8 shows a process chart of a heat treatment method for an oxide film according to a third embodiment of the present invention. In FIG. 8, 1 is a core tube, 2 is a boat, 3 is gas, 4
Is a substrate on which the BPSG deposited on the boat 2 (hereinafter referred to as a substrate). All BPSG is formed by atmospheric pressure CVD using silane, phosphine, and diborane as raw materials, and contains 6.5 mol% of P ₂ O _5.
As described above, the one containing 7.0 mol% or more of B ₂ O ₃ was used. Figure 8 (A)
(B) (C) are the substrates 4 placed on the boat 2 in each process of thermal history.
2 shows the position relative to the core tube 1. FIG. 9 is a thermal history diagram of the oxide film heat treatment method according to the third embodiment of the present invention.

The operation of the oxide film heat treatment method of the third embodiment constructed as described above will be described below.

In the inserting step 21, the substrate 4 is placed on the boat 2 and inserted into the core tube 1 as shown in FIGS. 8 (A) to 8 (B). Next, after the temperature raising process 22 is completed, in the heat treatment process 23, heat treatment is performed at a temperature of 900 ° C. or higher. On board 4
Since the viscosity coefficient of BPSG decreases in the heat treatment process 23, it becomes flat with time due to surface tension and the like. Then, in the temperature lowering process 24, while keeping the substrate 4 inside the core tube 1 as shown in FIG. 8 (B), 20 [l / mi of nitrogen was used as gas 3 in the core tube 1.
n] and the temperature was lowered to below 850 ° C. In this example, the temperature was lowered to 850 ° C at 5 [° C / min]. More preferably
Cool down at a rate of 7 [° C / min] or more. Then, in a take-out step 25, the substrate 4 is taken out together with the boat 2 into the atmosphere as shown in FIG.

FIG. 10 shows a principle diagram for suppressing the generation of precipitates according to the present invention. As described above, according to this embodiment, in the temperature lowering process 24, the gas 3 in the core tube 1 is 20 [l / min].
By inflowing at a flow rate of BPS, as shown in FIG.
Boron, phosphorus, oxygen, etc. in the gas phase near the G surface can be removed from the vicinity of the BPSG surface, and no precipitate is generated. Also,
Due to the cooling effect of the gas 3, crystal growth in the solid phase of BPSG is suppressed as shown in FIG.

FIG. 11 shows when the flow rate of the gas 13 is changed.
It is a figure which shows the number of the deposits produced in a 6-inch wafer. The condition as shown in FIG. 11 was that the temperature was lowered from 900 ° C to 850 ° C at a temperature decreasing rate of 5 [° C / min]. As can be seen from FIG. 11, the occurrence of precipitation can be suppressed by introducing the gas 3 at a flow rate of 20 [l / min].

Although nitrogen was flown as the gas 3 in this embodiment, the same effect can be obtained by using other gas such as oxygen. Further, in the present embodiment, the temperature was lowered to 850 ° C in the temperature lowering process 24, but it may be up to 850 ° C to any temperature.

(Embodiment 4) FIG. 12 is a process diagram of a heat treatment method for an oxide film according to a fourth embodiment of the present invention. In FIG. 12, 41 is a core tube, 42 is a boat, 43 is a water cooling tube, 44 is a substrate on which the BPSG is deposited on the boat 42, and 45 is an inert gas. BPSG is all silane,
It was formed by atmospheric pressure CVD using phosphine and diborane as raw materials, and contained P ₂ O ₅ at 6.5 mol% or more and B ₂ O ₃ at 7.0 mol% or more. 12 (A), (B), and (C) show the position of the substrate 44 placed on the boat 42 with respect to the core tube 41 in each process of thermal history. The thermal history of this example is similar to that of FIG.

The operation of the oxide film heat treatment method of the fourth embodiment having the above-described structure will be described below.

The steps until the BPSG is flattened in the heat treatment step 23 are the same as those in the third embodiment, and therefore will be omitted.
After that, in the extraction process 24, the inert gas is
As 45, nitrogen is introduced at a flow rate of 15 [l / min] and cooling water is flown through the water cooling tube 43 while filling the core tube 41 with nitrogen, and at a speed of 7 [° C / min] or higher, 850 ° C or lower. Cool down to. In this example, the temperature was lowered to 850 ° C. 15 inert gas
At a flow rate of about [l / min] and at a temperature lowering rate of 5 [° C / min] or less, precipitation proceeds in BPSG and many precipitates with a diameter of 0.1 um to 0.5 um are generated on the BPSG surface.

FIG. 13 is a diagram showing the number of precipitates generated on a 6-inch wafer when the temperature lowering rate is changed. The conditions shown in Fig. 13 are 900 ° C to 850 ° at a nitrogen flow rate of 15 [l / min].
The temperature was lowered to C. As can be seen from FIG. 13, precipitation can be suppressed by lowering the temperature to 850 ° C. or lower at a cooling rate of 7 [° C./min] or higher. Then take out process
At 25, the boat 42 is removed to the atmosphere.

As described above, according to this embodiment, the temperature during which the precipitate is formed is lowered to a temperature lower than the temperature range where the precipitate is formed in the temperature lowering process without giving the time,
As shown in FIG. 10 (B), growth in BPSG is suppressed and no precipitate is generated. In this embodiment, the cooling rate of 7 [° C / min] or more can be easily realized by providing the water cooling tube 43 around the core tube 41. Also, the core tube 41
By filling the inside with nitrogen, which is an inert gas 45, as shown in FIG. 10 (C), the supply of oxygen, water vapor, etc. from the atmosphere can be cut off, and crystal growth in the gas phase can also be suppressed. No precipitate is generated.

In this embodiment, 15 [l of the inert gas 45 is used.
/ min], but it may be filled with the inert gas 45.

(Embodiment 5) FIG. 14 is a process diagram of an oxide film heat treatment method according to a fifth embodiment of the present invention. In FIG. 14, 61 is a core tube, 62 is a boat, 63 is a vacuum pump, 64 is a substrate on which BPSG is deposited, and 65 is a shutter for keeping the core tube in vacuum. BPSG is all silane,
It was formed by atmospheric pressure CVD using phosphine and diborane as raw materials, and contained P2O5 at 6.5 mol% or more and B2O3 at 7.0 mol% or more.

FIGS. 14A, 14B, 14C and 14D show the position of the substrate 64 placed on the boat 62 with respect to the core tube 61 in each process of thermal history. The thermal history of this example is similar to that of FIG.

The operation of the oxide film heat treatment method of the third embodiment having the above structure will be described below.

In the inserting step 21, the substrate 63 is placed on the boat 62 and inserted into the core tube 61 as shown in FIGS. 14 (A) to 14 (B). Next, after the temperature raising process 22 is completed, in the heat treatment process 23, heat treatment is performed at a temperature of 900 ° C. or higher. Board 64
The upper BPSG has a smaller viscosity coefficient in the heat treatment process 23 and becomes flat with time due to surface tension and the like. Then, in the temperature lowering process 24, the substrate 64 is placed on the core tube 61 as shown in FIG.
The shutter 65 was closed while the inside of the reactor was kept inside, and the pressure inside the core tube 61 was lowered by the vacuum pump 63. In this example, 0.
Lowered to below 5 bar. After that, or while lowering the atmospheric pressure, the temperature was lowered to 850 ° C or lower. In this embodiment, at 5 [° C / min]
The temperature was lowered to 850 ° C. More preferably, the temperature is lowered at a rate of 7 [° C / min] or more. After that, in the take-out process 25, the pressure in the core tube 61 is set to 1 atm, and then, from FIG.
Take out the boat 62 into the atmosphere as shown in.

FIG. 15 is a diagram showing the number of deposits generated on a 6-inch wafer. The conditions shown in FIG. 15 are the cooling rate.
The temperature was lowered from 900 ° C to 850 ° C at 5 [° C / min]. As can be seen from Fig. 15, the atmospheric pressure is reduced to 0.5 atm or less, and 7 [° C / mi]
It can be seen that precipitation can be suppressed by lowering the temperature to 850 ° C or lower at a rate of n] or higher.

As described above, according to this embodiment, the temperature lowering process
By lowering the time at which the precipitate is formed to a temperature lower than the temperature range at which the precipitate is formed at 24 without giving,
As shown in FIG. 10 (B), growth in BPSG is suppressed and no precipitate is generated. Further, by lowering the atmospheric pressure in the core tube 51 in the temperature lowering process 24, boron, phosphorus, oxygen, etc. on the BPSG surface can be removed from the vapor phase near the BPSG as shown in FIG. Since it is suppressed, no precipitate is generated.

Although the atmospheric pressure is lowered only in the temperature lowering process 24 in this embodiment, the atmospheric pressure may be lowered from the heat treatment process 23 or the temperature raising process 22.

In the third, fourth and fifth embodiments of the present invention, BP
All SGs containing P2O5 at 6.5 mol% or more and B2O3 at 7.0 mol% or more were used. This is because if the concentration of P2O5 or B2O3 is lower than this concentration, it is necessary to raise the heat treatment temperature for reflowing and flattening or to lengthen the heat treatment time, which causes a problem in manufacturing the semiconductor device.

In the third, fourth and fifth embodiments of the present invention, the heat treatment temperature is all set to 900 ° C. or higher. This is because if the heat treatment temperature is lower than 900 ° C, the flatness is deteriorated due to insufficient reflow.

In the third, fourth and fifth embodiments of the present invention, BP
As SG, all those formed by atmospheric pressure CVD using silane, phosphine, and diborane as raw materials were used, but those using other raw material gases such as TEOS gas or those formed by other forming methods such as plasma CVD may be used. Needless to say.

In the third, fourth, and fifth embodiments of the present invention, an electric furnace in which one of the core tubes is open to the atmosphere is used. However, the boat around which the substrate is placed is covered with a tube, and the boat is placed in the core tube together with the tube. It goes without saying that a device that can be inserted into the tube and that allows gas to flow into the tube or a device that has a take-out chamber through which gas can flow when taking out the substrate from the core tube in the temperature lowering step may be used.

[0056]

According to the method of manufacturing a semiconductor device according to claim 1 of the present invention, by increasing the distance between the semiconductor substrates, the concentration of boron, phosphorus, etc. floating in the heat treatment atmosphere can be increased. It is possible to make it relatively thin with respect to the semiconductor substrate, perform heat treatment for planarization without causing precipitation of particles, and then form wiring such as aluminum with good yield, and The characteristics can be remarkably improved.

According to the semiconductor device manufacturing method of the second aspect of the present invention, the plurality of semiconductor substrates are loaded into the heat treatment furnace in a state where they are set in the semiconductor substrate carrying jig at predetermined intervals, and the heat treatment furnace is loaded. One control factor in the step of performing a heat treatment in accordance with a predetermined temperature profile to reflow the dielectric containing impurities formed on each semiconductor substrate to flatten the substrate surface,
The conditions under which the impurities evaporated from the dielectric during the heat treatment cannot be crystallized are set to suppress the generation of precipitates on the semiconductor substrate. If the atmosphere during heat treatment is selected as one control factor, it is possible to terminate the dangling bonds of the atoms that compose the dielectric film containing impurities such as the BPSG film, and planarize without causing the precipitation of particles. Heat treatment is performed, and then wiring such as aluminum is formed with a good yield, so that the characteristics of the element thus formed can be remarkably improved.

If the flow rate of the atmospheric gas during the heat treatment is selected as one control factor, boron and phosphorus vaporized from the reactive element BPSG are blown off from the surface of BPSG, and the cooling effect is enhanced, so that the precipitates are formed. Does not occur.

If the furnace pressure during the heat treatment is selected as one of the control factors, precipitates will not be generated by removing the reactive element from the BPSG surface.

If the temperature lowering rate in the temperature lowering process of the heat treatment is selected as one control factor, precipitates are not generated by lowering the temperature range in which the precipitates are generated without giving the growth time of the precipitates.

[Brief description of drawings]

FIG. 1 is a sectional view showing a processed wafer placed on a boat of a heat treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a processed wafer placed on a boat of a heat treatment apparatus in a conventional example.

FIG. 3 is a diagram in which the relationship between the wafer interval and the number of precipitated particles is plotted on a log scale in arbitrary units.

FIG. 4 is a diagram showing a profile of a flow rate of a gas flowing into an electric furnace and a temperature of the electric furnace in a heat treatment step in a second embodiment of the present invention.

FIG. 5 is a diagram showing an experimental result based on the same example.

FIG. 6 is a diagram showing a mechanism in which a pyrogenic atmosphere in an example of the present invention suppresses particle deposition of a BPSG film.

FIG. 7: MO immediately after heat treatment of the BPSG film in the example
Cross section of S-type transistor

FIG. 8 is a process diagram of a heat treatment method for an oxide film according to a third embodiment of the present invention.

FIG. 9 is a thermal history diagram of a heat treatment method for an oxide film in the example.

FIG. 10 is a principle diagram in which the generation of precipitates is suppressed by the present invention.

FIG. 11 is a diagram showing the number of precipitates generated on a 6-inch wafer when the gas flow rate is changed.

FIG. 12 is a process drawing of the heat treatment method for the oxide film in the fourth embodiment of the present invention.

FIG. 13 is a diagram showing the number of precipitates generated on a 6-inch wafer when the cooling rate is changed.

FIG. 14 is a process drawing of the heat treatment method for the oxide film in the fifth embodiment of the present invention.

FIG. 15 is a diagram showing the number of precipitates generated on a 6-inch wafer when the pressure is changed.

FIG. 16 is a process diagram of a conventional oxide film heat treatment method.

FIG. 17 is a thermal history diagram of a conventional heat treatment method for an oxide film.

FIG. 18: Principle of generation of this precipitate

[Explanation of symbols]

9 Boat Inserting Process 10 Furnace Temperature Stabilization Period 11 Temperature Raising Process 12 Temperature Decreasing Process 13 Boat Extraction Period 14 Heat Treatment Period 15 Oxygen Filling Period 16 Residual Hydrogen Reaction Period 32 Pyrogenic Atmosphere Period 25 Unsaturated Bond 26 Negatively Charged Boron 27 Positive Phosphorus 28 charged negatively 28 Hydrogen ion terminating negatively charged boron 29 Hydroxide ion 30 terminating positively charged phosphorus 30 Hydrogen radical terminating unsaturated bond of silicon 31 Hydroxylation terminating unsaturated bond of silicon Thing radical

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H01L 21/90 R 7353-4M (72) Inventor Toyokazu Fujii 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yuka Terai 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Shinichi Imai 1006, Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Invention Hiro Yamamoto, 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yasushi Naito, 1006, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A plurality of semiconductor substrates are loaded into a heat treatment furnace in a state where they are set on a semiconductor substrate carrying jig at predetermined intervals, and heat treatment is performed in the heat treatment furnace according to a predetermined temperature profile to obtain each semiconductor. In a method of manufacturing a semiconductor device including a step of flattening a substrate surface by reflowing a dielectric containing impurities formed on a substrate, a substrate in which impurities evaporated during heat treatment at the predetermined intervals are adjacent to each other A method for manufacturing a semiconductor device, characterized in that the interval is set so that it cannot adhere to the surface. 2. A plurality of semiconductor substrates are set in a semiconductor substrate carrying jig at a predetermined interval and are loaded into a heat treatment furnace and heat-treated in the heat treatment furnace according to a predetermined temperature profile to obtain each semiconductor. In a method for manufacturing a semiconductor device including a step of reflowing a dielectric containing impurities formed on a substrate to flatten the surface of the substrate, one control factor in the heat treatment step is A method for manufacturing a semiconductor device, characterized in that the conditions in which impurities evaporated from are not crystallized are set so as to suppress the generation of precipitates on the semiconductor substrate. 3. A method of manufacturing a semiconductor device according to claim 2, wherein the control factor is an atmosphere during the heat treatment. 4. The method of manufacturing a semiconductor device according to claim 2, wherein one control factor is a flow rate of an atmospheric gas during the heat treatment. 5. A method of manufacturing a semiconductor device according to claim 2, wherein one of the control factors is a furnace pressure during the heat treatment. 6. A method of manufacturing a semiconductor device according to claim 2, wherein one control factor is a temperature lowering rate in a temperature lowering process of heat treatment.